1. Field of the Invention
The present invention relates to the processing of thermally developable recording materials and more specifically to improved apparatus for heating such recording materials in sheet or web form.
2. Description of the Prior Art
Various imaging materials are known which utilize heat development following an imagewise exposure, e.g., by electrical charge, light or other forms of electromagnetic radiation; and many different devices have been utilized for thermally processing such materials. Common requirements for such devices are a well controlled and uniform application of heat, a rapid and efficient heat transfer to minimize energy usage and a reliable feed means which obviates material jams and conserves the power required for material transport.
Various approaches have been utilized, e.g., hot air heating, infrared heating, microwave heating, etc.; however, a simple and common approach has been conductive heating by moving sheet or web to be developed in intimate contact with a heated member. One common configuration for implementing the last mentioned approach utilizes a rotating heated drum, on which the sheet or web is moved from an entrance zone to an exit zone around the drum periphery. To maintain the sheet in intimate contact with the drum during rotation along the development path, a stationary support, e.g., a belt, or blanket, or shoe, has been located around the drum periphery, usually spring-biased into contact with the rotating drum. These processors often rely on the friction force between the drum and copy material, which is higher than the friction force between the copy material and stationary support, to effect transport of the copy material through the processing zone. Another, somewhat similar, kind of apparatus utilizes a stationary heated member, (e.g., a drum or platen) over which a continuous belt is moved to transport the copy material and hold it in close contact with the heated member. In this latter configuration the frictional force between the moving belt and copy material is greater than between the stationary heated member and sheet.
In both configurations described above high drive force requirements can be encountered, particularly when large width material is to be processed. Also, the high frictional forces and contact pressures utilized in such systems can damage the sheet or web material.